MANILA : Five people died and four others are believed to have also been killed when part of a coal mine collapsed on a remote central Philippine island on Friday, the provincial governor said.

The nine workers were using heavy machinery to remove sea water from the open-pit mine when a wall collapsed and buried them, Governor Rhodora Cadiao said. Heavy rains had also reportedly drenched the area, she added. “They were buried in mud and water. (The missing) are presumed dead already,” Cadiao told ABS-CBN television.

Mining operations were suspended following the incident and an investigation has been launched. Eight other miners who survived said sea water had been seeping into the pit for months, the governor said. Five people were killed in a similar incident at the mine in 2013. “Precautionary measures should have been in place,” the governor said. “This will undergo investigation. I hope there is no negligence on the part of the contractor.”

Semirara Mining and Power Corp., which owns the mine, said it was investigating in coordination with the government. “Management has condoled with the families of the victims and is giving them full support,” it said in a statement. The open-pit mine is on an island around four hours by boat from the central island of Antique, a fishing province in the Visayas islands, and one hour by plane from the capital Manila.